Feedback relating to the heart beat or heart rate is oftentimes given to inform a user about his or her physical state. For instance, sportsmen use heart rate information to optimize their performance. The measured heart rate may be presented by certain training devices, so that sportsmen may check to see if their heart rate was within a certain range. The feedback is often given visually, by means of a screen, or audibly. For example, the heart beats may be indicated by visual or audible signs that pulse simultaneous with every heart beat, and/or a sound may be generated when the heart rate exceeds a certain predefined maximum.